Some members of society have difficulty walking due to health problems. To provide mobility to these people, power wheelchairs have been developed. Powered wheelchairs often have six wheels including a pair of center wheels, a pair of rear wheels, and a pair of front wheels. Typically, one pair of wheels is driven by, and directly connected to, a drive. The drive wheels are typically fixed to the wheelchair and not capable of being repositioned to accommodate different sized occupants.
In cases where the wheelchair is a rear-wheel drive wheelchair the front wheels are configured to ride on the ground surface during normal operation and provide stability to the wheelchair during such operation. Typically, these front wheels have the capability to swivel about a vertical axis and are referred to as “casters.” When the wheelchair is driving in a forward direction the front wheels are configured to overcome an obstacle such as a curb. Therefore, these front wheels are connected to a suspension that allows them to rotate about a pivot as the wheelchair is overcoming the obstacle. In some cases the suspensions may cause the front wheels to at first rotate counterclockwise into the obstacle which may be undesirable. Additionally, certain suspensions do not maintain the swivel axis of the casters in a substantially vertical orientation, which may cause the front casters to catch while the wheelchair is turning.
The rear wheels, on the other hand, are fixed and often times referred to as anti-tip wheels. The anti-tip wheels may be suspended above the ground plane on which the wheelchair rests. The suspension of the anti-tip wheels allows the wheelchair to clear small obstacles such as a curb that may be in the path of travel of the wheelchair. In this case, where the wheelchair is a rear-wheel drive wheelchair, the anti-tip wheels may inhibit the wheelchair from overcoming the obstacle as the wheelchair is backing over the obstacle. Therefore, it may be desirable to provide a wheelchair with an anti-tip system that overcomes this problem.